The carbonic anhydrase inhibitor described above is disclosed in U.S. Pat. No. 4,797,413 which also discloses a process for preparing the racemic modification of the alkyl 3-(thien-2-ylthio)butyrate and its homologs. The prior art process comprises addition of the 2-thienylthiol across the double bond of a substituted acrylic acid: ##STR4## followed by synthesis of the final diastereomeric product, the isomers of which must be separated and each resolved to obtain the most active (S,S)-enantiomer. The isomer separations result in an automatic loss of the bulk of the chemical product.
It is therefore an object of this invention to provide a chiral intermediate for the synthesis of a chiral final product more economically than previously possible.
It is also an object of this invention to provide a process for the synthesis of the chiral intermediate.